''Tarphyeras'' is a genus of tarphyceratid with whorls rounded in cross section, having a deeply impressed dorsum and a ventral to subcentral

siphuncle The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and ...

, known from the Lower

Ord Ord or ORD may refer to: Places * Ord of Caithness, landform in north-east Scotland * Ord, Nebraska, USA * Ord, Northumberland, England * Muir of Ord, village in Highland, Scotland * Ord, Skye, a place near Tarskavaig * Ord River, Western Austral ...

Canad Canad may refer to: * Sanjak of Çanad, an Ottoman-era district * Magyarcsanád, known in Serbian as Čanad, a village in Hungary * Cenad, known in Serbian as Čanad, a commune in Romania See also * Canad Inns, a chain of hotels * Canard (disambi ...

) of North America. It differs from '' Campbelloceras'' in that ''Campbelloceras'' is only slightly impressed, from '' Centrotarphyceras'' in that ''Centrotarphyceras'' is subquadrate and has a central siphuncle, and from ''

Trocholites ''Trocholites'' is a tarphycerid genus in the family Trocholitidae from the Middle and Late Ordovician with a gradually expanding, weakly ribbed shell; whorls in contact, dorsum slightly impressed; cross section depressed, venter and sides rounded ...

'' in that although ''Trocholites'' is subcircular in cross section, the siphuncle is subdorsal. ''Taphyceras'' may be derived from ''Campbelloceras'' through development of tighter coiling and a deeper impression along with a smaller

that may be further offset from the venter. ''Tarphyceras'' was named by Hyatt in 1894.

References

* Furnish and Glenister 1964,Nautiloidea - Tarphycerida, K354, in The Treatise on Invertebrate Paleontology Vol K; Teichert and Moore, (eds) GSA and U of Kansas Press,1964 {{Taxonbar, from=Q7686584 Tarphycerida Prehistoric nautiloid genera Paleozoic life of Newfoundland and Labrador Paleozoic life of Quebec